Brick for masonry stoves what to choose

Owners of country houses in our time, when thinking over the issues of heating housing have a very wide choice. The range of boiler equipment and all necessary components for creating an effective heating system, with reference to the existing conditions - is extremely wide. Nevertheless, many owners want to have a real brick stove in their house. This - and a kind of tribute to the traditions, and the creation of a special coziness, and the availability of a fail-safe "helper" in case of emergency.

Brick masonry is a rather complicated process, requiring considerable professional skills. Usually this is entrusted to experienced peer-masters, whose services are constantly in demand. However, many Russians are so "arranged" that they want to try everything on their own. To do this, it is necessary to find a qualitative, operation-tested scheme-order, which is most suitable for the size and functionality of the particular place of construction. Well, the stove itself should be made of quality material with a well-prepared solution. This publication will consider the brick for laying the furnace which one to choose for a particular building department, how to assess the quality, what errors should be avoided.

Even if a master stove is invited, information on quality brick will be useful. Unfortunately, a lot in this field is engaged in frank "shabashnikov", whose main goal - to break as much money from the owners, overstate the overhead, while buying is not the best quality material. Therefore, it will be superfluous to control the purchase of a brick, which is better to be carried out together with the master. In any case, it will be possible to avoid unnecessary mutual reproaches.

Furnace sections and main loads falling on them

The novice master first of all must understand that the stoveconsists of different departments, each of which experiences its own "bouquet" of loads of very different plan - thermal, mechanical, chemical, moisture and even abrasive - in particular, the pipe head is subject to constant exposure to the winda. Therefore, a brick for various elements of this structure can be used in various ways. You can briefly see in the figure) it is not an order - it's just a schematic representation of the basic design of the furnace).

The furnace is a rather heavy structure, therefore it requires a solid foundation( item 1).A concrete slab is usually cast, but there is no need to "drag" it into the room, since it is a powerful accumulator and a conductor of cold from the ground. Therefore, it will be optimal to arrange it so that it is below the floor level( key 3).And at the desired height, above the floor level, for the base under the further laying of the furnace itself, it is better to lay out two to three continuous rows of bricks( post 4).They are separated from the concrete pit by a layer of waterproofing( item 2).Naturally, this basis must withstand the load of the entire mass of the furnace, so the main rate here is made on the strength of the brick. In addition, the lower possible exposure to negative temperatures, so it is important and frost resistance of the material.

The area of ​​the furnace( item 5) is subjected to maximum heating by direct flame, and the temperatures here can be critically high. Therefore, a special refractory brick, chamotte or, more rarely, quartz, is used.

The areas around the furnace, the whole labyrinth of chimney internal channels( pos.6) also experiences significant thermal loads, although already incomparable with the furnace itself. It requires a high-quality heat-resistant ceramic brick.

Of course, you always want the oven located indoors to look beautiful. Therefore, the upper cladding layer( item 7) must also comply with certain rules. For cases when the stove with the masonry under the screed is conceived, a well-treated facial brick is applied, both of conventional shape and figured. It is possible to apply a brick and with any beautiful textured surface. In the event that the plans are for furnishing the stove, for example, by plastering or tiling, external brick data does not already play a role. On the contrary, a somewhat uneven surface of the ordinary brick is even preferable for better adhesion to the mortar. But in any case, the brick must be high-quality, necessarily solid, with a high heat capacity and good heat transfer, since the outer surface of the furnace must warm up well and radiate heat into the room.

All that is above the main gate valve( key 11) can be assigned to the chimney section( key 9).This site, like no other, is under pressure from the external environment. It would seem that the temperature of the exhaust gases in it is not so high. However, changes in temperature and humidity in areas above the ceiling( item 8), and even more so - above the roof( item 10), can reach very significant values. So, on the street there can be a frosty frost, and in the chimney channel will be about 200 ÷ 400 ° C.Plus to this - atmospheric precipitation, condensation loss, saturation of exhaust gases with chemically aggressive substances - all this affects the material very destructively.

Optimum - use two types of bricks - for internal ducts, increased durability, and for external cladding - with minimal thermal conductivity to minimize the temperature difference and thus the condensate volume.

The main parameters of the brick

In the future, during the consideration of varieties of bricks will have to operate several concepts that characterize the material. First of all, this is the size of the brick. According to the established old tradition, we use a single brick of length( D) of 250 mm, a width( W) of 120 mm and a height of( B) of 65 mm in our regions.

However, there may be other sizes, and this should be paid attention when buying the material. Several standard sizes of a different format are listed in the table:

Brick type	Often used designation	Dimensions, mm	Dimension designation
Length( D)	Width( W)	Height( H)
Normal size brick( single)	TO	250	120	65	1 NF
Standard brick "Euro"	KE	250	85	65	0,7 NF ​​
Bricks thick	KU	250	120	88	1,4 NF
Single bricks modular	KM	288	138	65	1,3 NF
Bricks thickened with horizontal voids	KUG	250	120	88	1,4 NF

There is also a so-called furnace module, with dimensions of 230× 125 × 65.Although it is already considered obsolete, some schemes are designed for it. By the way, a whole line of refractory bricks is produced for it, including narrowed and narrowed ones with reduced height: 230 × 114 × 65 and 230 × 114 × 40 mm.

When choosing the scheme-ordering, it is mandatory to specify the format of the brick for the design, in order to avoid subsequently unpleasant "surprises".

For the laying of arch arches, some curly elements of the oven, for exterior decoration special brick formats can be used.

So, for the vaults are used wedge shaped bricks( with an edge or end taper).The dimensions of the narrowed side in this case are indicated through a fraction, for example: 230 × 114 × 65/45.

For exterior finishing bricks with rounded corners or other non-standard configuration are used. All this should be reflected in the scheme of the order and the table attached to it with a list of necessary materials.

• Vintage brick strength. This indicator shows the level of mechanical load that a material can withstand without the appearance of deformation, destructuring, cracking, crumbling, etc.

The strength grade is indicated by the letter value M and the number that indicates the level of the permissible load in kgf / cm².For example, for the laying of any of the furnace sections a brick of the brand not lower than M150 is required. If the stove is massive, two-story, then it is often necessary to use higher brands: M200 or M250.But it's not worth pursuing too high rates. The fact is that to achieve M300 ÷ M500 grades, special synthetic additives are introduced into the molding mixture during the production process. For the walls of the house this is not critical, but for an oven that experiences a significant thermal load - this is unacceptable. In addition, and the price of such brands will be much higher.

• Frost resistance of bricks.

This parameter is shown in the letter F and the symbol. The number shows the minimum number of cycles of freezing and thawing of bricks without losing their operational, including strength properties.

Although this parameter would seem to be less important for laying the furnace, it is worth paying attention to, especially when selecting materials for those departments that can be exposed to negative temperatures - this is the foundation and the chimney. By the way, the higher this index, the more stable the brick is to any basically sharp temperature differences.

• Thermal conductivity of bricks.

The furnace is, first of all, a thermo-technical structure, and its machines must store heat well and give it to the premises. For such purposes, a brick with a thermal conductivity index of not less than 0.61 W / m × ° C is used. The exception is permissible for the external finishing of the chimney, located in the attic and outdoors - there the thermal insulation qualities of the material are more likely to benefit.

• Hygroscopicity, that is, the ability of a material to absorb moisture. As a rule, it is expressed as a percentage of the weight of the brick. This parameter should be borne in mind for the choice of material for the kiln departments, where it is necessary or likely to contact the wet environment - again, the foundation and the chimney. The lower hygroscopicity, the better in this case.

Types of bricks by material and manufacturing technology

Now, let's move on to considering the types of bricks, immediately accompanying with remarks, for what purposes they can be used.

Silicate brick

Silicate brick externally attracts with impeccable regularity of its forms, smooth surfaces, a variety of color solutions. It is made from a mixture of purified quartz sand and calcareous additives( an approximate percentage of 90 to 10, but there may be variations).For the highest quality raw materials comes a special cleaning, both from interspersing associated minerals, and from organic materials.

The resulting mass is subjected to molding and pressing under high pressure under a certain temperature regime, and the structure of the resulting products is sufficiently dense. But such a brick is good for internal partitions, and even for facing buildings, and then with the condition of its protective processing. But for furnaces such a material of application does not find. Silicate is very poorly kept on clay mortar, and for our case this is a prerequisite. The second disadvantage is that the silica brick is not resistant to temperature changes, and will necessarily absorb moisture, which will lead to its rapid destruction. And the heat capacity of the material is low - the oven will give off heat too quickly and cool down.

For a foundation, it also does not suit - due to the proximity to soil moisture and not outstanding strength indicators. The only place where it is possible to apply it with great care is the outer lining of the chimney, but even there it is better to refuse from such an experiment.

Hyperpressed brick

This type of brick is most often produced from limestone screenings( coquina, dolomite, limestone, marble, etc.), and portland cement is added as a binder, about 10% of the total mass. Raw materials should be prepared with strict water proportions to ensure proper maturation of cement. Bricks undergo the stage of molding and pressing, also with observance of certain technological requirements for the moisture content of the mass, temperature and pressure level on the press. As a result, blocks with a clear geometry of the shapes are obtained, smooth or with an inverse pattern, often imitating, for example, wild rock.

Despite the fact that similar bricks seem to have good indices of brand strength - with observance of the manufacturing technology it reaches M200 ÷ M300, and frost resistance is characterized as F100 ÷ F150, hygroscopicity is low - for kiln works such materialnot suitable.

- Firstly, such a brick is almost completely lacking any plasticity - it does not withstand the stresses of fracture, and when shrinking the furnace will necessarily crack.

- Secondly, the calcareous base of bricks does not like high temperature heating - when exposed to heat, such rocks begin to release carbon dioxide and absorb plenty of water. Hence, a long oven made of hyperpressed bricks will not survive.

- And thirdly, the density of the brick is very high, and the stove construction turns out to be too massive, absolutely not justified, without any "dividends" from the performance qualities of the material.

Hyperpressed brick is good for finishing works - facing of facades or socles, construction of fences, etc. In the field of stove construction, he can think of, perhaps, only one reasonable application - it is the finishing of street barbecue complexes, in those places where the thermal effect from the combustion chamber is excluded. In such conditions, he will fully demonstrate his positive qualities.

Ceramic bricks

It is ceramic bricks - what you need for laying stoves and fireplaces. The basis for production is natural clay, and the performance characteristics of the finished product depend on the quality of raw materials and the technology of its cleaning, processing, molding and roasting.

There are many varieties of ceramic bricks, and not every one is like stove works. Much depends on the type of feedstock, on the features of the technology, on strict compliance and temperature conditions, and on the duration of firing. Minor violations - and the resulting material will no longer meet the declared characteristics and under extreme operating conditions will not last long. Probably, that's why among the professional-pechatnikov already formed a stable opinion about brick producers, a kind of rating of factories and companies that can be trusted, and "black lists" of products that are insufficient or frankly of poor quality.

Let's walk through the basic varieties of ceramic clay brick.

• First of all, it should immediately be stipulated that for bricklaying of the furnace only solid brick is used, without internal voids. Hollow bricks due to air interlayers do not possess the required thermal conductivity, they are not able to accumulate and give off heat. In addition, due to the special structure, the hollow bricks do not have resistance to thermal shocks - when the temperature drops sharply, internal stresses reach critical values ​​that lead to the appearance of cracks and the destruction of blocks.

The only exception can be only the outer layer of the chimney pipe finishing - there the increased values ​​of the thermal resistance work in the "right direction".But at the same time the internal channel itself must necessarily be composed of high-quality full-bodied material. And the hollow brick itself in such operating conditions should have strengths not lower than M150, and frost resistance - at least F35.

• Red clay brick must necessarily pass the stage of high-temperature roasting. The fact is that you can run into a brick-raw atmospheric drying( this technology is usually used in regions with hot climates).

Such material for the furnace is completely unsuitable - due to the effect of temperature drops it will quickly begin to crumble altogether in trash.

• The next important difference between different types of ceramic bricks is the molding technology. There is also a need for special care when choosing, as far from any material is suitable for making stove works.

So, we can distinguish three main types of molding:

- Semi-dry pressing.

With this method of production, clay mass with a moisture content of about 8 ÷ 12% is put into molds, excess water is squeezed out of it, and only after that the final pressing of products and their high-temperature firing takes place. This technology allows you to get bricks with smooth surfaces( or with a given relief pattern) and increased accuracy of the geometry of the blocks. It would seem an excellent option for stoves - however, this is not so.

- Plastic molding

The difference is that the initial clay mass has a much higher humidity - the water content in the raw material reaches 20 or more percent. On extrusion plants, formations are formed from the mass. Which are then cut into modules of the required size and fed to a high temperature firing.

This kind of brick is required for the laying of furnaces. The fact is that a large moisture content is not only the necessary plasticity during molding. Water is an active participant in physicochemical processes occurring in clay mass during the firing period. This is what gives the bricks the required heat resistance, the necessary strength and porosity, the ability to "breathe" and store heat - those qualities that are necessary for furnaces.

To distinguish even outwardly the bricks made by these technologies are not difficult.

The picture above( item 1) shows a semi-dry pressing brick. It, as already noted, gives smooth surfaces of faces.

Bottom( item 2) - brick, obtained by the technology of plastic molding. On its surfaces, one can always notice traces of cutting from a common layer - these are small scores, lines, grooves, etc.

- There is another technology for brick forming - slip casting e, in which almost semi-liquid mass is poured into molds, and then firing occurs, but at much lower temperatures. This approach is used to obtain high-precision predefined shapes, for example, in the manufacture of decorative pieces of decoration. But not one department of the furnace, even as a cladding, such a brick does not fit - from the effects of elevated temperatures it crumbles and quickly begins to crumble.

By the way, since the question of molding technology is being considered, one can immediately make a remark about the actively discussed brick of the Obolsky plant, which is often presented as a stove. Its characteristic feature is the presence on the bed of protuberances, which, in theory, should specify the thickness of the seam and impart a higher adhesion of the bricks to the mortar.

There are no words, the brick is good and convenient in work. But only if you listen to the opinions of the stove workers who tried it in practice, the picture becomes not so rosy. With frequently changing thermal loads, especially after a long stagnation of the furnace, such a brick began to give through cracks - just to burst. And the matter, apparently, in what has already been mentioned above - it is impossible to impart a similar shape to the technology of plastic molding, and the brick is clearly produced by the method of semi-dry pressing.

Such material may well come up for furnishing a stove or fireplace, but laying out the foundation, the "body" of the heating structure, is completely unacceptable. Moreover, it is not suitable for furnace sections that either contact fire, or are located in a high-temperature zone adjacent to the combustion chamber or internal heat exchange chimneys.

Clinker brick

In fact - this is a kind of ceramic bricks, only in the manufacture of a slightly different technology is used.

First, special refractory grades of clay are selected for its production. Secondly, the firing temperature is much higher than that used for the production of conventional building ceramic bricks. As a result of firing, a clay mixture with mineral additives is sintered almost to a glassy mass, which causes the highest strength( above M300) characteristics and frost resistance( F100 and more).

The material, it would seem, is excellent, but in stove construction it is not so widely used. There are several reasons for this. Firstly, clinker bricks are rather expensive material, and it is unprofitable to erect it completely. Secondly, the very high density of clinker makes the stove construction extremely heavy. And thirdly, as experienced ovens say, the clinker furnace will not "breathe" as it does with high-quality ceramic material.

However, clinker bricks may be needed. For example, if a large oven is being built, it needs a solid base, and the clinker is perfect for laying out the starting foundation rows. Another area of ​​application is the internal channel of the chimney, up to the head, which can be lined with another brick outside. In such conditions, the high resistance of the clinker to mechanical stresses and temperature differences, to the aggressive effects of the chemical constituents of the combustion products, will be very useful.

By the way, from clinker bricks sometimes fold compact stoves, the type of burzhuek. And as a result, according to their thermo-technical characteristics, such structures become comparable with massive cast-iron furnaces. This option will be an excellent solution for the bath.

Refractory chamotte bricks

Qualitative ceramic bricks are capable of withstanding heating to 700 ÷ 900 ° C, in clinker this figure can reach up to 1200 ° C, but this may not be enough for the furnace departments that directly contact fire and incandescent combustion products. Therefore, in most scheme-ordering, you can find areas marked with a special color - so the masonry is produced by refractory chamotte bricks.

For the production of chamotte bricks, special grades of refractory clay enriched with special mineral additives are used. The firing is carried out at temperatures above 1500 ° C, and as a result, a material is obtained which, without loss of its strength, can withstand temperatures of up to 1300-1400 ° C.

Fireclay bricks are easy to distinguish by the characteristic fine-grained structure of high density and color - usually cream colors predominate. When splitting, such a brick splits and does not crumble, and breaks up into large fragments.

In principle, such a brick is suitable for any department of the furnace, but this is not practiced solely because of the high cost of the material. It is used for laying or lining the combustion chambers and the initial section of chimneys where pyrolysis gases can burn out.

The sizes of fireclay bricks are presented in a wide variety. They can fully correspond to ordinary brick or have their own parameters, for example, narrowed or with a reduced width of blocks. This is sometimes very convenient when laying a firebox - it will be easier to fit into the overall "body" of the furnace, laid out from a conventional heat-resistant ceramic brick.

Pay attention to the illustration above. As you can see, fireclay bricks do not bind to ceramic in any place, and a special solution is required for its laying. But in the picture below - obviously illiterate work, which is unlikely to give a good result.

The fact is that ceramic and fireclay bricks have completely different thermal characteristics, including the coefficient of linear thermal expansion. Such masonry is doomed to internal instability of the seams and deformation of the entire structure. Conversely, between the materials, a gasket is usually made, for example, from an asbestos sheet, so that the necessary temperature clearance is provided.

As a refractory, quartz bricks can also be used. Outwardly, they descend something with chamotte material, but differ even more dense and homogeneous structure.

This material is very expensive, and does not withstand the aggressive chemical environment very well, therefore its application in domestic stove construction is rather limited. Quartz brick is characterized by a reduced linear expansion, so it is predominantly used in places where the layout of metal parts is planned.but it is best to apply it for inserting a chimney tooth - a special figured element, due to which a powerful infrared reflection of the heat flow into the room occurs. There, the quartz brick will show all its advantages to the full.

How to evaluate brick when choosing?

When choosing a brick, you should immediately get acquainted with its characteristics, declared by the manufacturer - any batch of material from a bona fide supplier is always accompanied by the relevant documents. On the floor to believe the sellers undesirable, and to acquire the material better in respectable firms, rather than in a spontaneous market - to run into a poor quality product is very simple.

If the brand of brick for manufacturing technology, heat resistance, vintage resistance and frost resistance meets the requirements, it is necessary to evaluate the quality of the batch.

• First of all, a visual inspection and comparison of several bricks of their one batch is carried out. They should not have serious differences in linear dimensions - a deviation of not more than 2 mm is allowed. Absolutely inadmissible are any distortion of shape, screw-like curvature of the faces, crumbling at the corners and edges, pronounced heterogeneity of the material, foreign inclusions, signs of overt burn.

The mica film does not say anything good and good on the surface of the brick - this material will not show resistance to frequent temperature changes.

• Experienced cookers always check the selected material by ear. So, with careful tapping with a hammer, a quality brick should produce a clearly discernible clear and clear sound. If the sound is deaf, then, most likely, either the raw materials were not of the best quality, or the production went with a violation of technology, and the bricks turned out to be not sufficiently dried and hardened.

This test also gives one more result: after a light hammer blow, no chips or deep marks should remain on the surface of the brick.

Video: recommendations for checking the quality of bricks for the

• It is advisable to negotiate with the seller for a "crash test".The bricks from the chosen batch are split - it becomes possible to evaluate its strength and density of the material itself - it should not crumble to dust, but be chipped away by large fragments. Much will tell the cut of the brick - the internal structure is usually more "frank" than the surface.

The homogeneity of the structure, the presence of voids is estimated. It should be absolutely excluded large foreign impurities, including clay. Their presence indicates gross violations of raw material preparation technology.

Video: Comparative extreme tests of quality of oven bricks

• The color of the cut must also be uniform throughout the depth( 1st grade).The obvious predominance of a light shade in the center indicates that the brick has not been properly fired, underexposed, and its strength will be far from the declared characteristics - usually this material is classified as grade 2.Dark spots suggest otherwise - the brick is burned, which can lead to increased fragility( grade 3).And the one and the other option for the furnace is better not to buy, or use them in thermally unloaded areas.

furnace. - So, a tempered brick of grade 3 may well be suitable for laying the foundation foundation - it is characterized by increased resistance to compression, and more is not required.

- A for brick facing, especially in cases where further finishing is planned by plastering or ceramic tiles, it is possible to apply brick 2 grades. Its heat capacity will be enough, increased porosity even on the hand "breathing" of the furnace, and after a rough surface it will be better to retain the finishing material.

- But for domestic channels, only a first-class, properly annealed brick is used - here it will have a serious thermal load. Important is the quality of the surface - there should be no big scoring, the remaining field of cutting of the plastic mass in the production process. The point is that for chimneys the most smooth surface is required in order to minimize possible accumulation of soot.

By the way, almost everywhere there are situations when on one pallet are found bricks of all three varieties. Therefore, experienced stoves always precede the beginning of the work by careful sorting of the material in order to rationally use it with minimal losses.

• By the way, for some departments of the furnace it is quite possible to use the material left after disassembling old structures - quite often it is even offered for purchase at a rather favorable price. But it should be remembered that only bricks are considered suitable, which did not experience direct contact with extremely high temperatures - these are the upper and lower rows of masonry and the areas located far from the combustion chamber.

The material to which the furnace was laid is not suitable for reuse.

• And, finally, a few words about the manufacturer of the material. Brick factories and throughout Russia, and in the near abroad - a great many. You can not indiscriminately criticize one or extol others - for sure in each region there are "authorities" in the production of such products. And here we just list a few companies whose bricks are, as they say, "on hearing", and is popular with many masters.

Such companies include:

- Vitebsk production - JSC "Ceramics", and experienced masters also distinguish products by shops. So, a certain difference is made between the "Workshop number 1" and "Workshop number 2".The difference is not so much in the performance characteristics of the product, as in the intended use of products - for hidden or external masonry.

- "Borovichi Combine of Building Materials", JSC "BKSM", Novgorod Region. Products of the brand "Borovichi" has a very long-deserved reputation, the quality of the brick itself is excellent, although some criticisms can be found about the "dancing" geometry of individual modules.

- Again Borovichi, but already a combine of refractories, OJSC "BKO".It is interesting that the history of this enterprise has already passed for a century and a half! Fireclay bricks produced by BKO OJSC are of the highest quality, and enjoy unquestioned authority among the masters of the stove business.

- OJSC "Pobeda LSR", St. Petersburg, which has consolidated several enterprises for the production of construction materials, has won stable positions in this market. In the line of its products - high-quality ceramic bricks, widely used by craftsmen-stove.

- Their foreign manufacturers can be allocated to the company "LODE" and "Wienerberger Group".In the range of products are widely presented materials designed specifically for masonry stoves and fireplaces.

Video: a brief overview of the brick for furnaces and fireplaces by LODE